Telecommunications apparatus and methods

ABSTRACT

A base station for transmitting system related information in a mobile telecommunications network. The base station is configured to transmit system information for the cell provided by the base station and to broadcast a version synchronisation signal, wherein the version synchronisation signal provides version information regarding the current version of the system information for the cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/EP2018/061213, filedMay 2, 2018, which claims priority to EP 17169821.0, filed May 5, 2017,the entire contents of each are incorporated herein by reference.

BACKGROUND Field

The present disclosure relates to telecommunications apparatus andmethods.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Third and fourth generation mobile telecommunication systems, such asthose based on the 3GPP defined UMTS and Long Term Evolution (LTE)architecture, are able to support more sophisticated services thansimple voice and messaging services offered by previous generations ofmobile telecommunication systems. For example, with the improved radiointerface and enhanced data rates provided by LIE systems, a user isable to enjoy high data rate applications such as mobile video streamingand mobile video conferencing that would previously only have beenavailable via a fixed line data connection. The demand to deploy suchnetworks is therefore strong and the coverage area of these networks,i.e. geographic locations where access to the networks is possible, maybe expected to increase ever more rapidly.

Future wireless communications networks will be expected to routinelyand efficiently support communications with a wider range of devicesassociated with a wider range of data traffic profiles and types thancurrent systems are optimised to support. For example it is expectedfuture wireless communications networks will be expected to efficientlysupport communications with devices including reduced complexitydevices, machine type communication (MTC) devices, high resolution videodisplays, virtual reality headsets and so on. Some of these differenttypes of devices may be deployed in very large numbers, for example lowcomplexity devices for supporting the “The Internet of Things”, and maytypically be associated with the transmissions of relatively smallamounts of data with relatively high latency tolerance. Other types ofdevice, for example supporting high-definition video streaming, may beassociated with transmissions of relatively large amounts of data withrelatively low latency tolerance. Yet other types of device, for exampleused for autonomous vehicle communications, may be characterised by datathat should be transmitted through a network with very low latency andvery high reliability. A single device type might also be associatedwith different data traffic profiles/characteristics depending on theapplication(s) it is running. For example, different consideration mayapply for efficiently supporting data exchange with a smartphone when itis running a video streaming application (high downlink data) ascompared to when it is running an Internet browsing application(sporadic uplink and downlink data) or being used for voicecommunications by an emergency responder in an emergency scenario.

In view of this there is expected to be a desire for future wirelesscommunications networks, for example those which may be referred to as5G or new radio (NR) system/new radio access technology (RAT) systems,as well as future iterations/releases of existing systems, toefficiently support connectivity for a wide range of devices associatedwith different applications and different characteristic data trafficprofiles.

One example area of current interest in this regard includes theso-called “The Internet of Things”, or IoT for short. The 3GPP hasproposed in Release 13 of the 3GPP specifications to developtechnologies for supporting narrowband (NB)-IoT and so-called enhancedMTC (eMTC) operation using a LTE/4G wireless access interface andwireless infrastructure. More recently there have been proposals tobuild on these ideas in Release 14 of the 3GPP specifications withso-called enhanced NB-IoT (eNB-IoT) and further enhanced MTC (feMTC),and in Release 15 of the 3GPP specifications with so-called furtherenhanced NB-IoT (feNB-IoT) and even further enhanced MTC (efeMTC). See,for example, [1], [2], [3], [4]. At least some devices making use ofthese technologies are expected to be low complexity and inexpensivedevices requiring relatively infrequent communication of relatively lowbandwidth data.

The increasing use of different types of terminal devices associatedwith different traffic profiles gives rise to new challenges forefficiently handling communications in wireless telecommunicationssystems.

SUMMARY

Aspects and features of the present disclosure are defined in theappended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 schematically represents some aspects of a LTE-type wirelesstelecommunication system which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 2 provides a schematic diagram of a structure of a downlink of awireless access interface of a mobile communications system operatingaccording to an LTE standard;

FIG. 3 schematically represents the transmission of the synchronisationsignals in an FDD LTE system;

FIG. 4A illustrates an example of a synchronisation signal transmissionindicating a system information version;

FIG. 4B illustrates another example of a synchronisation signaltransmission indicating a system information version;

FIG. 5 illustrates an example of use of resources for transmitting andreceiving a synchronisation signal;

FIG. 6 illustrates another example of use of resources for transmittingand receiving a synchronisation signal;

FIG. 7 illustrates an example method in accordance with the presentdisclosure; and

FIG. 8 illustrates another example method in accordance with the presentdisclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 provides a schematic diagram illustrating some basicfunctionality of a mobile telecommunications network/system operating inaccordance with LTE principles and which may be adapted to implementembodiments of the disclosure as described further below. Variouselements of FIG. 1 and their respective modes of operation arewell-known and defined in the relevant standards administered by the3GPP (RTM) body, and also described in many books on the subject, forexample, Holma H. and Toskala A [5]. It will be appreciated thatoperational aspects of the telecommunications network which are notspecifically described below may be implemented in accordance with anyknown techniques, for example according to the relevant standards.

FIG. 1 provides a schematic diagram of a mobile telecommunicationssystem, where the system includes infrastructure equipment comprisingbase stations 101 which are connected to a core network 102, whichoperates in accordance with a conventional arrangement which will beunderstood by those acquainted with communications technology. Theinfrastructure equipment 101 may also be referred to as a base station,network element, infrastructure apparatus, enhanced Node B (eNodeB) or acoordinating entity for example, and provides a wireless accessinterface to the one or more communications devices within a coveragearea or cell represented by a broken line 103. One or more mobilecommunications devices 104 may communicate data via the transmission andreception of signals representing data using the wireless accessinterface. The core network 102 may also provide functionality includingauthentication, mobility management, charging and so on for thecommunications devices served by the network entity.

The mobile communications devices of FIG. 1 may also be referred to ascommunications terminals, user equipment (UE), terminal devices and soforth, and are configured to communicate with one or more othercommunications devices served by the same or a different coverage areavia the network entity. These communications may be performed bytransmitting and receiving signals representing data using the wirelessaccess interface over the two way communications links.

The communications system may operate in accordance with any knownprotocol, for instance in some examples the system may operate inaccordance with a 3GPP Long Term Evolution (LTE) standard.

As shown in FIG. 1, one of the base stations 101 a is shown in moredetail to include a transmitter 110 for transmitting signals via awireless access interface to the one or more communications devices orUEs 104, and a receiver 112 to receive signals from the one or more UEswithin the coverage area 103. A controller 114 controls the transmitter110 and the receiver 112 to transmit and receive the signals via thewireless access interface. The controller 114 may perform a function ofcontrolling the allocation of communications resource elements of thewireless access interface and may in some examples include a schedulerfor scheduling transmissions via the wireless access interface for bothan uplink and the downlink.

In this example, the infrastructure equipment 101 a comprises atransmitter 110 for transmission of wireless signals, a receiver 112 forreception of wireless signals and a controller 114 configured to controlinfrastructure equipment 1001 a to operate in accordance withembodiments of the present disclosure as described herein. Thecontroller 114 may comprise various sub-units, such as a scheduler, forproviding functionality in accordance with embodiments of the presentdisclosure as explained further below. These sub-units may beimplemented as discrete hardware elements or as appropriately configuredfunctions of the controller 114. Thus, the controller 114 may comprise aprocessor which is suitably configured/programmed to provide the desiredfunctionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. The transmitter 110, receiver 112 andcontroller 114 are schematically shown in FIG. 1 as separate elementsfor ease of representation. However, it will be appreciated that thefunctionality of these units can be provided in various different ways,for example using a single suitably programmed general purpose computer,or suitably configured application-specific integratedcircuit(s)/circuitry. It will be appreciated the infrastructureequipment 101 a will in general comprise various other elementsassociated with its operating functionality, such as a scheduler. Forexample, although not shown in FIG. 1 for simplicity, the controller 114may comprise a scheduler, that is to say the controller 104 may providethe scheduling function for the base station.

An example UE 104 a is shown in more detail to include a transmitter 116for transmitting signals on the uplink of the wireless access interfaceto the eNodeB 103 and a receiver 118 for receiving signals transmittedby the base station 101 on the downlink via the wireless accessinterface. The UE 104 a also comprises a storage medium 122, such as asolid state memory or similar, for storing data. The transmitter 116,receiver 118 and storage medium 112 are controlled by a controller 120.In the embodiments of the present disclosure, the UE 104 a is a terminaldevice configured to operate using feMTC (Further Enhanced Machine TypeCommunications) or eNB-IoT (Enhanced Narrowband Internet of Things).

In this example, the terminal device 104 a comprises a transmitter 116for transmission of wireless signals, a receiver 118 for reception ofwireless signals, a controller 120 configured to control the terminaldevice 104 a and a storage medium 122. The controller 120 may comprisevarious sub-units for providing functionality in accordance withembodiments of the present disclosure as explained further herein. Thesesub-units may be implemented as discrete hardware elements or asappropriately configured functions of the controller 120. Thus thecontroller 120 may comprise a processor which is suitablyconfigured/programmed to provide the desired functionality describedherein using conventional programming/configuration techniques forequipment in wireless telecommunications systems. The transmitter 116,receiver 118 and controller 120 are schematically shown in FIG. 1 asseparate elements for ease of representation. However, it will beappreciated that the functionality of these units can be provided invarious different ways, for example using a single suitably programmedgeneral purpose computer, or suitably configured application-specificintegrated circuit(s)/circuitry. It will be appreciated the terminaldevice 104 a will in general comprise various other elements associatedwith its operating functionality, for example a power source, userinterface, and so forth, but these are not shown in FIG. 1 in theinterests of simplicity.

Mobile telecommunications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division modulation (OFDM) based wireless accessinterface for the radio downlink (so-called OFDMA) and a single carrierfrequency division multiple access scheme (SC-FDMA) on the radio uplink.The down-link and the up-link of a wireless access interface accordingto an LTE standard is presented in FIG. 2.

FIG. 2 provides a simplified schematic diagram of the structure of adownlink of a wireless access interface that may be provided by or inassociation with the base station of FIG. 1 when the communicationssystem is operating in accordance with the LTE standard. In LTE systemsthe wireless access interface of the downlink from a base station to aUE is based upon an orthogonal frequency division multiplexing (OFDM)access radio interface. In an OFDM interface the resources of theavailable bandwidth are divided in frequency into a plurality oforthogonal subcarriers and data is transmitted in parallel on aplurality of orthogonal subcarriers, where bandwidths between 1.4 MHzand 20 MHz bandwidth may be divided into orthogonal subcarriers. Not allof these subcarriers are used to transmit data. The number ofsubcarriers varies between 72 subcarriers (1.4 MHz) and 1200 subcarriers(20 MHz). In some examples the subcarriers are grouped to form ascheduling blocks. A resource block (RB) can consist of 12 sub-carriers.A narrowband in MTC can consist of 6 RBs or 72 subcarriers. Eachsubcarrier bandwidth may take any value but in LTE it is fixed at 15kHz. As shown in FIG. 2, the resources of the wireless access interfaceare also temporally divided into frames where a frame 200 lasts 10 msand is subdivided into 10 subframes 201 each with a duration of 1 ms.Each subframe 201 is formed from 14 OFDM symbols and is divided into twoslots 220, 222 each of which comprise six or seven OFDM symbolsdepending on whether a normal or extended cyclic prefix is beingutilised between OFDM symbols for the reduction of inter symbolinterference. The resources within a slot may be divided into resourcesblocks 203 each comprising 12 subcarriers for the duration of one slotand the resources blocks further divided into resource elements 204which span one subcarrier for one OFDM symbol, where each rectangle 204represents a resource element. The frame structure also contains primarysynchronisation signals (PSS) and secondary synchronisation signals(SSS): not shown in FIG. 2. The PSS occupies the central 62 subcarriersof the 7^(th) OMNI symbol of the first subframe and the 7^(th) OFDMsymbol of the 6^(th) subframe of the radio frame. The SSS occupies thecentral 62 subcarriers of the 6^(th) OFDM symbol of the first subframeand the central 62 subcarriers of the 6^(th) OFDM symbol of the 6^(th)subframe of the radio frame.

Before a terminal can use a cell provided by a base station, theterminal is expected to carry out a series of steps. For example, aterminal may be in a situation where it has not yet achievedsynchronisation after a long DRX period or after having being switchedon. A terminal would be expected to detect the cell and cell-ID usingthe Primary Synchronisation Signal (PSS) and Secondary SynchronisationSignal (SSS) to detect the cell, and then receive the System Information(MIB) from the Physical Broadcast Channel (PBCH) and further SystemInformation from the PDSCH. More specifically a terminal would have tofirst achieve time and frequency synchronisation with the cell,typically using the legacy PSS and SSS emitted by the base station.Then, the terminal will decode the PBCH to acquire the MIB. The MIBcontains amongst other things information for the terminal to acquirefurther System Information, namely SIB1 that is transmitted via thePDSCH. SIB1 contains scheduling information for acquiring the remainingSystem Information portions (other SIBs). A terminal operating incoverage enhanced mode (which can for example be a machine-type or IoTterminal) requires numerous repetitions to be able to decode the PBCHand PDSCH channels carrying the System Information. Example estimates ofthe expected acquisition times for the PSS/SSS, PBCH (MIB) and SIB1 areshown in Table 1 for a deep coverage scenario.

TABLE 1 Estimated 90% acquisition time at 164 dB MCL Channel 90%Acquisition Time (ms) PSS/SSS 850 PBCH (MIB) 250 PDSCH (SIB1) 750

Table 1 shows the 90-th percentile of the time required to detect eachsignal. As can be seen in this table, a significant amount of time andenergy needs to be spent on system information acquisition in the deepcoverage scenario, once synchronisation has been achieved. It can thusbe desirable to try to reduce or eliminate the time and/or power usedfor system acquisition, that is for acquiring the MIB and SIBs (usingthe current terminology).

Legacy terminals (MTC terminals or otherwise) use the existing PSS/SSSwhich occupy only 1 OFDM symbol each and are transmitted twice everyradio frame.

This is illustrated in FIG. 3 which represents the transmission of thesynchronisation signals in an FDD LTE system.

FIG. 3 schematically represents the transmission of the synchronisationsignals in an FDD LTE system. FIG. 3 shows a radio frame 306, dividedinto 10 subframes, SF0-SF9. Each of the subframes SF0-SF9 consists oftwo slots; for example, the subframe SF1 comprises slot 2 308 and slot 3310.

Here the PSS 302 (represented by hatching) is transmitted in the lastOFDM symbol of Slot 0 310 (Subframe 0, SF0) and Slot 10 312 (Subframe 5,SF5) whilst the SSS 304 (represented by a solid block) is transmitted inthe second to last OFDM symbol of Slot 0 (Subframe 0 SF0) and Slot 10(Subframe 5 SF5). Due to the synchronisation signals being transmittedwith a small amount of resources in both the time and frequency domains,in a coverage enhanced mode the resulting time needed to synchronisewith the cell can be much longer than desired.

In accordance with the present disclosure, there can be provided one ormore additional synchronisation signals/channels (such as one or morePSS/SSS-like signals) with a view to reducing the overall acquisitiontime. The additional synchronisation signal(s) can be used for terminalsto decide or estimate whether to acquire the system information orwhether the last system information they have used is still expected tobe up-to-date. Viewing from a different perspective, there is providedan arrangement wherein a new MTC Synchronisation Signal “MSS” istransmitted, wherein this MSS carries information related to systemacquisition.

In some examples, the additional synchronisation signal(s) can also betransmitted more frequently (i.e. more densely in the time dimension)than the conventional/existing PSS and SSS signals. This can enable aterminal using a coverage enhanced mode to accumulate the requirednumber of synchronisation samples more quickly.

In a first example aspect, the MSS has a different sequence and/orscrambling to that used for the PSS and SSS. Accordingly, legacyterminals would not be able to detect the MSS, which would otherwiseresult in the legacy terminals receiving the synchronisation signals andin advertently using these signals to synchronise to the cell in anerroneous manner. As mentioned above, it is expected that in many cases,the MSS would be denser, i.e. transmitted more often (e.g. transmittedin more OFDM symbols per slot and/or in more slots per radio frame) thanthe legacy PSS & SSS so that the terminal would be able to synchronisewith the cell faster than using only the conventional PSS & SSS.

The MSS can provide a number of different types of information regardingsystem acquisition system acquisition information). In an embodiment thesystem acquisition information can be an indication of SystemInformation “SI” change. An SI change can for example be indicated ifthere are any changes to the contents carried by the MIB and/or SIB. Ina legacy system, an SI change can be indicated via paging where aterminal then needs to blind detect for MPDCCH to receiving the paging.

According to the present disclosure, the SI change information can beindicated using a different MSS sequence/scrambling configuration(similar to the way that a different sequence or scrambling for thePSS/SSS signals can be used to signal the Cell ID).

The terminal can then attempt to decode the MSS based one of twohypotheses, that is a first hypothesis of a sequence and/or scramblingassuming SI change and a second hypothesis of another sequence and/orscrambling assuming no SI change. Hence by detecting the MSS the UE candecide whether to skip reading the SIBs (if there is no SI change) or toread the SIBs. This example recognises that SI changes are expected tobe rare and hence for a majority of the time, a UE would have alreadyacquired the latest SI and would therefore skip reading the SIBs in mostcases, thereby saving time and battery.

In some examples the MSS can indicate whether there has been a systeminformation change within a period preceding the transmission of theMSS, for example in the frame before the MSS transmission, in the last nsub-frames before the MSS transmission, or any other suitablepredetermined period.

In the discussion above, the MSS can indicate a system informationchange or alternatively no system information change through the MSSsequence/scrambling configuration applied. Hence the MSSsequence/scrambling configuration applied can be interpreted asproviding an MSS indicator with a value “0” or “1”.

In some examples, this change can be encoded either using “0” toindicate “no change” or “1” to indicate “SI has changed”. In otherexamples, the MSS can switch between “0” and “1” whenever there is achange and continue communicating the same “0” or “1” value until thenext change in system information. For example, if the MSS wasindicating “0” prior to a change, the MSS can then indicate “1” after anSI change and will continue to indicate “1” for as long as the SI doesnot change. This example is illustrated in FIG. 4A.

FIG. 4A illustrates an example of a synchronisation signal transmissionindicating a system information version, during a time period comprisingfour contiguous modification periods indicated by respectivedouble-headed arrows labelled M1-M4 and covering time periods,respectively, from τ0 to τ2, from τ2 to τ3, from τ3 to τ4, and from τ4to τ6.

A DRX cycle 402 extends from time τ1 to τ5 and comprises an ‘on’ period404 and an ‘off’ (or DRX mode) period 406.

MSS indicators 412 a-d are transmitted during the modification periodsM1-M4.

SI changes within modifications periods M2 and M3 are respectivelyindicated by arrows 408 and 410.

FIG. 4A shows that as the SI changes, the indicator changes from 0 to 1for the next modification period, then back to 0 after it changes again.As the SI has not changed for the last time period, it remains 0 duringthis time period. Although this example enables a straightforwardapplication and implementation, in some examples it also has somelimitations. For example, a terminal receiving the MSS at times τ₁ andτ₅ might not realise that the system information has changed (twice) andwould thus not attempt to receive the new system information.

FIG. 4B illustrates an alternative arrangement for an MSS providing a0/1 indicator (as in FIG. 4A, and like reference numerals are used forlike features) wherein a first of the two “0” or “1” values indicatesthat the system information has changed relative to a predeterminedperiod preceding the MSS transmission (the modification period), whereasthe other of the “0” and “1” values indicates that the systeminformation has not changed in this period. In this example themodification period is expected to correspond to a number of PSS/SSScycles. Although in practice, it is expected that an implementationsimilar to that of FIG. 4A would be preferred (as it provides anindication of the current version of system information regardless ofhow long ago it last changed), in some examples, an implementation asillustrated in FIG. 4B might be considered useful (depending for exampleon how long the DRX cycles are expected to be and depending on what themodification period will be configured to be).

In some examples, the system acquisition information can contain an SIversion. Similar to the previous example where the MSS indicatorswitches between 0 and 1 at every change, the terminal upon detectingthe MSS would be able to determine whether the SI has changed bycomparing the SI version that it has versus the SI version indicated bythe MSS. From one perspective, the example discussed above andillustrated in FIG. 4A can be viewed as having only two versions wherethe SI indicator can indicate version “0” or version “1”. Using a (moreadvanced) SI version can allow the SI change to indicate more than 2versions. This recognises that the terminal can be in a long DRX periodand hence may miss two or more SI indicator changes. For example, inFIG. 4A where only two version “0” or “1” can be indicated, the terminalDRX cycle 402 from time τ₁ to τ₅ spans four modification periods M1, M2,M3 and M4. In this example, the SI change can indicate version “0” or“1” and changes twice while the terminal is in the DRX mode 406.

More specifically, when the terminal wakes up at time τ₁ it detects theSI change indicator is set to “0” which is the same version as that inthe terminal's memory and hence there is no SI change indicated and theterminal goes back to sleep. During the terminal's sleep period, thereare two SI changes 408, 410: in modification period M2 (between time τ₂to τ₃) and M3 (between time τ₃ to τ₄) and hence during M2, the SI changeindicator 412 b toggles to “1” and during M3 it toggles 412 c to “0”.When the terminal wakes up at time τ₅, the SI version 412 d is “0” whichmatches the version in the terminal's memory and the terminal assumes nochanges to the SI. However, as the SI has changed twice already, theterminal may no longer have an up-to-date version of the SI. Hence byallowing the MSS to indicate more than two SI versions avoids the SIversions from wrapping around without the terminal noticing. Each SIversion can be represented by a separate sequence and/or scrambling.

In another example, the system acquisition information can be anindication of changes to the information carried by the MIB apart fromthe SFN. Apart from the System Frame Number “SFN” (which changes every 4radio frames in the MIB), the MIB carries information such as systembandwidth information as well as scheduling and configurationinformation for SIB1. Hence by detecting the MSS the terminal candetermine or estimate whether to skip reading the MIB (if it still hasthe correct SFN information) or to read the MIB. Accordingly,unnecessary decoding of the MIB can be reduced or avoided with such anarrangement.

In some examples, the MSS can be transmitted in a different narrowbandto that of the LTE PSS/SSS. The current LIE PSS & SSS are located in thecentral narrowband in a system bandwidth. By transmitting the MSS in adifferent narrowband, this can provide flexibility in scheduling theMSS. This can also allow the MSS to occupy contiguous resources in timewith a view to accelerating the acquisition process. It is noteworthythat if the MSS occupies the central 6 PRBs (central narrowbandcurrently used for PSS/SSS transmissions), it may not always be providedin time-contiguous resources. In particular, as the legacy PSS/SSS andMIB also occupy the central 6 PRBs and the MSS might have to be mappedto non-contiguous resources around these signals).

In some examples, the narrowband containing the MSS can be detected bythe terminal when it first switches on. For example, instead of (or inaddition to) scanning for PSS/SSS, it can scan for MSS to try tosynchronize to the cell. This can be particularly relevant for terminalsthat are not expected to be mobile (e.g. smart meters) which areunlikely to change cell and can then assume as a first hypothesis thatthe cell has not changed and the same cell has not changed the locationof the MSS. The location of the MSS can also be signalled by thenetwork, for example in SIB or in RRC configuration so that it can beused for re-acquisition (e.g. if the UE first connects to the cell usingthe PSS/SSS, it can read the system information or an RRC configurationthat informs the UE of the location of the MSS and the UE can use thatMSS in future acquisitions of the cell).

It should also be noted that the MSS can be used by an HD-FDD terminalduring its Uplink Compensation Gap “UGC” to re-acquire synchronisationafter a long uplink transmission. Here the terminal can switch to thedownlink narrowband containing the MSS. When an MSS is used that allowsthe terminal to synchronise more quickly (than for the legacy case wherethe LIE synchronises using the PSS/SSS), the duration of the UCG can bereduced compared to the legacy case.

In an example, if the terminal is configured to monitor MSS (or the UEsignals to the network that it can detect MSS), it applies a shorterUCG. This has the benefit of reducing the latency for transmission of ULmessages and can reduce terminal power consumption (since the terminalcan switch to a low power state earlier if it can complete an ULtransmission earlier).

In another embodiment the MSS can also indicate where the centralnarrowband is. This is especially relevant if MSS is used for initialacquisition (i.e. a “cold start”, when the terminal is first switchedon) where the terminal tries to detect for MSS and the MSS is in adifferent narrowband to that of the PSS/SSS & PBCH. Hence the MSS canindicate where (relative to the location of the MSS) the terminal canobtain the PBCH. In some cases, no indication can be interpreted asmeaning that both MSS and PBCH are located at the same frequency. Inother cases, even when the MSS and PBCH are located in the same band,the MSS may still include an indication of the location of the PBCH(i.e. in the same frequency band). Such indications can be transmittedby the use of different MSS sequences, or different scrambling appliedto MSS.

In an example, the set of possible MSS sequences is a function of theCell ID. The sequences in such a set of MSS sequences are used toindicate information as discussed herein. Here, for each Cell ID thereis a different set of sequences. Hence by detecting the MSS the terminalwill also learn of the Cell ID. This enables the MSS to be used forinitial acquisition, for example instead of the PSS and SSS.

While the MSS may be transmitted in the same narrowband, in otherexamples the MSS can use different bands and may rely on a “frequencyhopping” arrangement as will be discussed below.

In an example where Frequency Hopping (FH) is used for the MSS, this canprovide gain (e.g. frequency diversity gain) for the MSS, therebyreducing the number of samples required by a terminal in coverageenhanced mode, which in turn is expected to lead to faster systemacquisition. The frequency hopping pattern can be based on the Cell IDand/or configured by the network. It should be appreciated that whenfrequency hopping is used, it may be difficult for terminal to use MSSwhen it is first switched on (e.g. in the case where the MSS isfrequency hopped at known time intervals) and this may be used morefrequently in “warm start” situations).

Although the MSS can be transmitted at more than two (or more) frequencylocations for a FH arrangement (i.e. transmitted as two separatesignals), in the interest of conciseness, the examples below discuss twonarrowbands only (i.e. the MSS is transmitted in two separate frequencybands).

However the skilled person will appreciate that the same teachings canalso be applied to three or more bands.

FIG. 5 illustrates an example time period in a time dimension(illustrated by arrow 502) within a system bandwidth 504. Accordingly,in this example the MSS is transmitted by the eNodeB with FH using twonarrowbands continuously and the terminal frequency hops its receiver toreceive at one or the other of those frequency locations. The firstnarrowband (“narrowband A”) is represented by the diagonally hatchedregion 506 within the system bandwidth 504, and the second narrowband(“narrowband B”) is represented by the checkerboard region 508 withinthe system bandwidth 504. In this way, the terminal is able to achievefrequency diversity for the MSS without knowing a time-based hoppingpattern—that is, the terminal does not have to be aware of the time atwhich the MSS is transmitted as it is transmitted continuously in twonarrowbands. This example is illustrated in FIG. 5 which shows theeNodeB continuously transmitting MSS at two frequency locations(narrowband A 506 and narrowband B 508—see top time diagram). On theother hand, the terminal implements a hopping pattern between narrowbandA and narrowband B (receiving within resources indicated by the blackboxes 510 a-510 e in narrowband A 506 and within resources indicated bythe black boxes 512 a-512 f in the middle time diagram) and hencereceives a frequency hopped version of MSS (comprising the portions ofthe MSS transmitted in the first narrowband 506 which are received inthe resources 510 a-510 e and the portions of the MSS transmitted in thesecond narrowband 508 which are received in the resources 512 a-512e—see bottom time diagram in FIG. 5).

In yet another example (which can also be seen as a combination of thetime and frequency “hopping” discussed above), the eNodeB can transmitthe MSS at different frequency locations in overlapping blocks of time,as illustrated in FIG. 6 for example.

FIG. 6 illustrates the transmissions of the eNode3 using a firstnarrowband portion 608 (“narrowband A”) of the system bandwidth 504during a plurality of non-contiguous time periods illustrated bydiagonally hatched rectangles 602 a-602 e. In addition, the eNodeBtransmits using a second narrowband portion 610 (“narrowband B”) of thesystem bandwidth 504 during a plurality of non-contiguous time periodsillustrated by checkerboard-patterned rectangles 604 a-604 f.

This figure shows that the eNodeB can transmit the MSS in anon-contiguous fashion (in the time domain 606) at two differentfrequency locations (i.e. in a non-contiguous manner in the frequencydomain). The terminal can then frequency-hop between those frequencylocations 608, 610 at the expected MSS transmission time. In someexamples, the transmission of the MSS 602 a-602 e, 604 a-604 f is longerthan the expected receiving time 510 a-510 e, 512 a-512 f, therebycausing an “overlap” (see for example, the time period 612 of FIG. 6)wherein at a point in time the MSS is transmitted in two separate bands608, 610. This can for example assist with accommodating timing error atthe terminal provided that it is less than the “overlap” 612 shown inthe figure.

In an example, the terminal is informed or is always aware of the MSSphysical resources in the time and frequency domain. For example, theterminal may receive or have information that can include a narrowbandindex for the narrowband carrying MSS, information regarding the OFDMsymbol(s) carrying MSS, information regarding the MSS FH pattern (ifany) etc. This configuration of the MSS is particularly beneficial inthe following two cases:

-   -   Warm start. When the terminal has previously acquired and read        system information or has been in an RRC_connected state in a        cell, it can receive configuration information on that cell        (including the MSS configuration) that will allow the terminal        to receive the MSS when it re-acquires system information of        that cell. For example a stationary terminal that sleeps for a        long period of time can initially attempt to re-acquire the cell        using the configured MSS when it wakes from sleep. As it is        stationary it will likely be using the same cell as before it        went to sleep and might thus be able to confirm that its        existing SI (previously acquired) is still valid.    -   Mobility. The terminal can be informed of MSS configurations in        neighbour cells via Information Elements (“IEs”) in a neighbour        cell list. When the terminal performs neighbour cell        measurements, it can also then perform those neighbour cell        measurements directly on the MSS.

In a “cold start” case (when the terminal is likely unaware of MSSconfiguration of the cell), it can synchronise using either the legacyPSS SSS or using blind detection hypotheses on potential MSSconfigurations. However in some cases a terminal might be able to usethe MSS instead. For example a stationary terminal (e.g. smart meter)may first attempt to use its last MSS configuration for attempting afast system acquisition, if possible. If this fails, the terminal canthen fall back on the legacy techniques with the PSS/SSS. In someexamples, in a “cold start” case and where the terminal will try todetect either the PSS/SSS or MSS, the spacing between two PSS/SSS andMSS synchronization signals can be in a predefined multiple frequencyspacing. For example in an LTE environment, the frequency spacing, alsoreferred to as frequency raster, is a multiple of 100 kHz and the samefrequency spacing can be used between the PSS/SSS signal on one hand andthe MSS signal on the other hand.

More generally, in some cases the terminal may first attempt to gainsynchronisation using the MSS and the last MSS configuration it has. Ifit fails to synchronise using MSS (e.g. a timer expires before a MSS canbe detected), different options are available to the terminal and can beconfigured in the terminal.

Generally, the following functionalities (providing fallback mechanisms)may be implemented in a terminal:

-   -   Prioritise MSS:        -   It first attempts to gain synchronisation using MSS of            previously configured neighbour cells.        -   If unsuccessful, it then attempts to gain synchronisation            using PSS/SSS of the previous serving cell        -   If unsuccessful, it then attempts to gain synchronisation            using PSS/SSS of any cell    -   Prioritise serving cell        -   It first attempts to gain synchronisation using PSS/SSS of            the previous serving cell        -   If unsuccessful, it then attempts to gain synchronisation            using MSS of previously configured neighbour cells.        -   If unsuccessful, it then attempts to gain synchronisation            using PSS/SSS of any cell

The above fallback mechanisms may be beneficial for example if theeNodeB can change the configuration of its MSS (e.g. turn it on or off)or the terminal can move to cells that do not implement MSS, but onlyimplement the legacy PSS/SSS.

In an embodiment, the MSS can be transmitted at times derived from a DRXcycle. For example, the MSS may be transmitted only during UCG periodsof active terminals, or the MSS may be transmitted prior to pagingoccasions. This functionality can enable terminals that have previouslyconnected to the cell to synchronize more quickly (e.g. at pagingoccasions, for receiving mobile terminated messages), while minimizingthe resources used for MSS transmission. However terminals that wish totransmit mobile originated messages would have to wait for DRX cyclesbefore being able to synchronize and transmit those UL messages, thusincreasing latency for these terminals.

It is also noteworthy that although the MSS has been generally describedas a single signal, the skilled person will appreciate that in someexamples it may be provided as two or more separate signals. Forexamples, similarly to the use of two synchronisation signals PSS/SSSfor legacy synchronisation, the terminal may be able to search for anddetect two different signals, MSS1 and MSS2, to synchronise anddetermine system related information (e.g. indication of a change of ora version of system information).

FIG. 7 illustrates an example method in accordance with the presentdisclosure for providing an MSS-type signal in accordance withtechniques discussed herein. First, at S701, a base station is providedwherein the base station is configured to transmit system informationfor the cell it provides. For example the system information comprisesthe MIB and/or SIB as used in an LTE telecommunications system.

Then at S702, the base station broadcasts a version synchronisationsignal (e.g. MSS). The version synchronisation signal provides versioninformation regarding the current version of the system information forthe cell. Accordingly, this can reduce the number of cases where aterminal may attempt to receive the system information for the cell.

FIG. 8 illustrates another example method in accordance with the presentdisclosure. First, at S801, a version synchronisation signal (e.g. MSS)from the base station is detected by a terminal. The versionsynchronisation signal provides version information regarding thecurrent version of the system information for the cell.

Then, once the version synchronisation signal has been received, theterminal can determine, based on the version information, whether thecurrent version of the system information for the cell matches theversion of the system information stored in the terminal (S802).

If no match is found, the method proceeds to S803 and the terminalattempts to receive the system information provided by the base station.If on the other hand a match is found, the terminal can use the systeminformation stored in the terminal (S804).

Numerous modifications and variations of the present disclosure arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the disclosuremay be practiced otherwise than as specifically described herein.

In so far as embodiments of the disclosure have been described as beingimplemented, at least in part, by software-controlled data processingapparatus, it will be appreciated that a non-transitory machine-readablemedium carrying such software, such as an optical disk, a magnetic disk,semiconductor memory or the like, is also considered to represent anembodiment of the present disclosure.

It will be appreciated that the above description for clarity hasdescribed embodiments with reference to different functional units,circuitry and/or processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, circuitry and/or processors may be used without detracting fromthe embodiments.

Described embodiments may be implemented in any suitable form includinghardware, software, firmware or any combination of these. Describedembodiments may optionally be implemented at least partly as computersoftware running on one or more data processors and/or digital signalprocessors.

The elements and components of any embodiment may be physically,functionally and logically implemented in any suitable way. Indeed thefunctionality may be implemented in a single unit, in a plurality ofunits or as part of other functional units. As such, the disclosedembodiments may be implemented in a single unit or may be physically andfunctionally distributed between different units, circuitry and/orprocessors.

Although the present disclosure has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognize that various features of the described embodimentsmay be combined in any manner suitable to implement the technique.

In the present disclosure, method steps discussed herein may be carriedout in any suitable order and not necessarily in the order in which theyare listed. For example, steps may be carried out in an order whichdiffers from an order used in the examples discussed above or from anindicative order used anywhere else for listing steps (e.g. in theclaims), whenever possible or appropriate. Thus, in some cases, somesteps may be carried out in a different order, or simultaneously(entirely or in part) or in the same order. So long as an order forcarrying any of the steps of any method discussed herein is technicallyfeasible, it is explicitly encompassed within the present disclosure.

As used herein, transmitting information or a message to an element mayinvolve sending one or more messages to the element and may involvesending part of the information separately from the rest of theinformation. The number of “messages” involved may also vary dependingon the layer or granularity considered. For example transmitting amessage may involve using several resource elements in an LTE/5Genvironment such that several signals at a lower layer correspond to asingle message at a higher layer. Also, transmissions too or from aterminal may relate to the transmission of any one or more of user data,discovery information, control signalling and any other type ofinformation to be transmitted unless specified otherwise.

Also, whenever an aspect is disclosed in respect of an apparatus orsystem, the teachings are also disclosed for the corresponding method.Likewise, whenever an aspect is disclosed in respect of a method, theteachings are also disclosed for any suitable corresponding apparatus orsystem. Additionally, it is also hereby explicitly disclosed that forany teachings relating to a method or a system where it has not beenclearly specified which element or elements are configured to carry outa function or a step, any suitable element or elements that can carryout the function can be configured to carry out this function or step.For example any one or more of a mobile terminal, a base station or anyother mobile unit may be configured accordingly if appropriate, so longas it is technically feasible and not explicitly excluded.

It is noteworthy that even though the present disclosure has beendiscussed in the context of LTE and/or 5G, its teachings are applicableto but not limited to LTE, 5G or to other 3GPP standards. In particular,even though the terminology used herein is generally the same or similarto that of the 5G standards, the teachings are not limited to thepresent version of 5G and could apply equally to any appropriatearrangement not based on 5G and/or compliant with any other futureversion of an 5G or 3GPP or other standard

Respective features of the present disclosure are defined by thefollowing numbered examples:

Example 1. A base station for transmitting system related information ina mobile telecommunications network, the base station being configured

to transmit system information for the cell provided by the basestation,

to broadcast a version synchronisation signal, wherein the versionsynchronisation signal provides version information regarding thecurrent version of the system information for the cell.

Example 2. The base station of Example 1 further configured to broadcasta further synchronisation signal wherein the further synchronisationsignal is for use for terminals to achieve synchronisation with thecell.

Example 3. The base station of Example 2 further configured to broadcastthe version synchronisation signal more frequently than the furthersynchronisation signal.

Example 4. The base station of Example 2 or 3 further configured tobroadcast the further synchronisation signal periodically at a firsttime frequency and the version synchronisation signal periodically at asecond time frequency, the second time frequency being higher than thefirst time frequency.

Example 5. The base station of any one of Examples 2 to 4 furtherconfigured to broadcast the version synchronisation signal based on oneor both of:

a sequence that differs from a sequence used for transmitting thefurther synchronisation signal; and

a scrambling configuration that differs from a scrambling configurationused to transmit the further synchronisation signal.

Example 6. The base station of any one of Examples 1 to 5 furtherconfigured to broadcast the version synchronisation signal based on anumber, the number indicating the current version of the systeminformation for the cell, wherein the number is used to derive one orboth of a sequence and a scrambling configuration for transmitting theversion synchronisation signal.

Example 7. The base station of any one of Examples 1 to 6 wherein theversion information regarding the current version of the systeminformation for the cell comprises one or more of:

an indication that the current version of the system information haschanged compared to a previous version of the system information thatwas in use at a previous point in time;

an indication that the current version of the system information haschanged compared to a previous version of the system information thatwas in use at a previous point in time wherein the previous point intime is identified based on a predetermined time difference; and

an indication of a current version number, the version number beingincremented at each system information change, the version number beingselected from a circular list of n elements, with n≥2.

Example 8. The base station of any one of Examples 1 to 7 furtherconfigured to provide the version synchronisation signal as two or moreseparate signals forming together the version synchronisation signal.

Example 9. The base station of any one of Examples 1 to 8 furtherconfigured to broadcast the version synchronisation signal using two ormore separate frequency bands.

Example 10. The base station of Example 9 further configured tobroadcast the version synchronisation signal according to one or moreof:

a transmission of a first portion of the version synchronisation signalas a continuous signal in a first of the two or more separate frequencybands or as a non-contiguous signal in the first frequency band; and

a transmission of a second portion of the version synchronisation signalas a continuous signal in a second of the two or more separate frequencybands or as a non-contiguous signal in the second frequency band.

Example 11. Circuitry for a base station transmitting system relatedinformation in a mobile telecommunications network, wherein thecircuitry comprises a controller element and a transceiver elementconfigured to operate together to:

transmit system information for the cell provided by the base station,broadcast a version synchronisation signal, wherein the versionsynchronisation signal provides version information regarding thecurrent version of the system information for the cell.

Example 12. A method of transmitting system related information in amobile telecommunications network, the network comprising a base stationconfigured to transmit system information for the cell provided by thebase station, the method comprising:

broadcasting, by the base station, a version synchronisation signal,

wherein the version synchronisation signal provides version informationregarding the current version of the system information for the cell.

Example 13. The method of Example 12 further comprising broadcasting, bythe base station, a further synchronisation signal wherein the furthersynchronisation signal is for use for terminals to achievesynchronisation with the cell.

Example 14. The method of Example 13 wherein the version synchronisationsignal is transmitted more frequently than the further synchronisationsignal.

Example 15. The method of Example 13 or 14 wherein the furthersynchronisation signal is transmitted periodically at a first timefrequency and the version synchronisation signal is transmittedperiodically at a second time frequency, the second time frequency beinghigher than the first time frequency.

Example 16. The method of any one of Examples 13 to 15 wherein theversion synchronisation signal is transmitted based on one or both of:

a sequence that differs from a sequence used for transmitting thefurther synchronisation signal; and

a scrambling configuration that differs from a scrambling configurationused to transmit the further synchronisation signal.

Example 17. The method of any one of Examples 12 to 16 wherein theversion synchronisation signal is transmitted based on a number, thenumber indicating the current version of the system information for thecell, wherein the number is used to derive one or both of a sequence anda scrambling configuration for transmitting the version synchronisationsignal.

Example 18. The method of any one of Examples 12 to 17 wherein theversion information regarding the current version of the systeminformation for the cell comprises one or more of:

an indication that the current version of the system information haschanged compared to a previous version of the system information thatwas in use at a previous point in time;

an indication that the current version of the system information haschanged compared to a previous version of the system information thatwas in use at a previous point in time wherein the previous point intime is identified based on a predetermined time difference; and

an indication of a current version number, the version number beingincremented at each system information change, the version number beingselected from a circular list of n elements, with n≥2.

Example 19. The method of any one of Examples 12 to 18 wherein theversion synchronisation signal is provided as two or more separatesignals forming together the version synchronisation signal.

Example 20. The method of any one of Examples 12 to 19 wherein theversion synchronisation signal is transmitted using two or more separatefrequency bands.

Example 21. The method of Example 20 wherein the version synchronisationsignal is transmitted according to one or more of:

a transmission of a first portion of the version synchronisation signalas a continuous signal in a first of the two or more separate frequencybands or as a non-contiguous signal in the first frequency band; and

a transmission of a second portion of the version synchronisation signalas a continuous signal in a second of the two or more separate frequencybands or as a non-contiguous signal in the second frequency band.

Example 22. A terminal for receiving system information in a mobiletelecommunications network, the network comprising a base stationconfigured to transmit system information for the cell provided by thebase station, the terminal being configured to:

detect a version synchronisation signal from the base station, theversion synchronisation signal providing version information regardingthe current version of the system information for the cell;

determine, based on the version information, whether the current versionof the system information for the cell matches the version of the systeminformation stored in the terminal; and

use, if the current version of the system information for the cellmatches the version of the system information stored in the terminal,the system information stored in the terminal.

Example 23. The terminal of Example 22 further configured to:

attempt, if the current version of the system information for the celldoes not match the version of the system information stored in theterminal, to receive the system information provided by the basestation.

Example 24. The terminal of Example 22 or 23 further configured to:

determine, if the current version of the system information for the celldoes not match the version of the system information stored in theterminal, location information from the version synchronisation signal,the location information identifying time and frequency resources forreceiving the system information provided by the base station; and

attempt to receive the system information using the locationinformation.

Example 25. Circuitry for terminal for receiving system information in amobile telecommunications network, the network comprising a base stationconfigured to transmit system information for the cell provided by thebase station, wherein the circuitry comprises a controller element and atransceiver element configured to operate together to:

detect a version synchronisation signal from the base station, theversion synchronisation signal providing version information regardingthe current version of the system information for the cell;

determine, based on the version information, whether the current versionof the system information for the cell matches the version of the systeminformation stored in the terminal; and use, if the current version ofthe system information for the cell matches the version of the systeminformation stored in the terminal, the system information stored in theterminal.

Example 26. A method of receiving system information at a terminal in amobile telecommunications network, the network comprising a base stationconfigured to transmit system information for the cell provided by thebase station, the method comprising the terminal:

detecting a version synchronisation signal from the base station, theversion synchronisation signal providing version information regardingthe current version of the system information for the cell; determining,based on the version information, whether the current version of thesystem information for the cell matches the version of the systeminformation stored in the terminal; and

if the current version of the system information for the cell matchesthe version of the system information stored in the terminal, using thesystem information stored in the terminal.

Example 27. The method of Example 26 further comprising the terminal:

if the current version of the system information for the cell does notmatch the version of the system information stored in the terminal,attempting to receive the system information provided by the basestation.

Example 28. The method of Example 26 or 27 further comprising theterminal:

if the current version of the system information for the cell does notmatch the version of the system information stored in the terminal,determining location information from the version synchronisationsignal, the location information identifying time and frequencyresources for receiving the system information provided by the basestation; and

attempting to receive the system information using the locationinformation.

Example 29. A mobile telecommunications network, the network comprisinga base station configured t transmit system information for the cellprovided by the base station and comprising a terminal, the networkbeing configured to:

broadcast, via the base station, a version synchronisation signal to theplurality of terminals, wherein the version synchronisation signalprovides version information regarding the current version of the systeminformation for the cell;

detect, via the terminal, the version synchronisation signal from thebase station; determine, via the terminal and based on the versioninformation, whether the current version of the system information forthe cell matches the version of the system information stored in theterminal;

use, via the terminal and if the current version of the systeminformation for the cell matches the version of the system informationstored in the terminal, the system information stored in the terminal.

Example 30. A method of using system related information in a mobiletelecommunications network, the network comprising a base stationconfigured to transmit system information for the cell provided by thebase station, the method comprising:

broadcasting, by the base station, a version synchronisation signal tothe plurality of terminals, wherein the version synchronisation signalprovides version information regarding the current version of the systeminformation for the cell;

detecting, by a terminal of the plurality of terminals, the versionsynchronisation signal from the base station;

determining, by the terminal and based on the version information,whether the current version of the system information for the cellmatches the version of the system information stored in the terminal;

if the current version of the system information for the cell matchesthe version of the system information stored in the terminal, theterminal using the system information stored in the terminal.

Accordingly, from one perspective there has been provided a method oftransmitting system related information in a mobile telecommunicationsnetwork, the network comprising a base station configured to transmitsystem information for the cell provided by the base station. The methodcomprises broadcasting, by the base station, a version synchronisationsignal (e.g. MSS), wherein the version synchronisation signal providesversion information regarding the current version of the systeminformation for the cell. This enables a terminal to determine whetherto attempt to receive the system information. In an arrangement wherethe base station broadcasts a further synchronisation signal (e.g. PSSand/or SSS) that is for use for terminals to achieve synchronisationwith the cell (wherein the terminals can then also receive the systeminformation), the version synchronisation signal can be used instead orin addition to the further synchronisation signal when the terminalwould normally attempt to receive system information (e.g. after a warmor cold start). As the version synchronisation signal is provided as asynchronisation signal, it can be received by terminals even if they arenot yet synchronised with the cell.

Accordingly, from another perspective, there has been provided aterminal for receiving system information in a mobile telecommunicationsnetwork, the network comprising a base station configured to transmitsystem information for the cell provided by the base station. Theterminal is configured to detect a version synchronisation signal fromthe base station, the version synchronisation signal providing versioninformation regarding the current version of the system information forthe cell; determine, based on the version information, whether thecurrent version of the system information for the cell matches theversion of the system information stored in the terminal; and use, ifthe current version of the system information for the cell matches theversion of the system information stored in the terminal, the systeminformation stored in the terminal.

REFERENCES

-   [1] RP-161464, “Revised WID for Further Enhanced MTC: for LTE,”    Ericsson, 3 GPP TSG RAN Meeting #73, New Orleans, USA, Sep. 19-22,    2016-   [2] RP-161901, “Revised work item proposal: Enhancements of NB-IoT”,    Huawei, HiSilicon, 3 GPP TSG RAN Meeting #73, New Orleans, USA, Sep.    19-22, 2016-   [3] RP-170732, “New WID on Even further enhanced MTC for LTE,”    Ericsson, Qualcomm, 3 GPP TSG RAN Meeting #75, Dubrovnik, Croatia,    Mar. 6-9, 2017-   [4] RP-170852, “New WID on Further NB-IoT enhancements,” Huawei,    HiSilicon, Neul, 3 GPP ISG RAN Meeting #75, Dubrovnik, Croatia, Mar.    6-9, 2017-   [5] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based    radio access”, John Wiley and Sons, 2009

The invention claimed is:
 1. A base station for transmitting systemrelated information in a mobile telecommunications network, the basestation being configured to: transmit system information for a cellprovided by the base station; broadcast a first synchronization signalfor use for terminal to achieve synchronization with the cell; andbroadcast a second synchronisation signal more frequently than the firstsynchronisation signal, wherein the second synchronisation signalprovides version information regarding the current version of the systeminformation for the cell.
 2. The base station of claim 1, furtherconfigured to: broadcast the first synchronisation signal periodicallyat a first time frequency and the second synchronisation signalperiodically at a second time frequency, the second time frequency beinghigher than the first time frequency.
 3. The base station of claim 1,further configured to: broadcast the second synchronisation signal basedon one or both of: a sequence that differs from a sequence used fortransmitting the first synchronisation signal; and a scramblingconfiguration that differs from a scrambling configuration used totransmit the first synchronisation signal.
 4. The base station of claim1, further configured to broadcast the second synchronisation signalbased on a number, the number indicating the current version of thesystem information for the cell, wherein the number is used to deriveone or both of a sequence and a scrambling configuration fortransmitting the second synchronisation signal.
 5. The base station ofclaim 1 wherein the version information regarding the current version ofthe system information for the cell comprises one or more of: anindication that the current version of the system information haschanged compared to a previous version of the system information thatwas in use at a previous point in time; an indication that the currentversion of the system information has changed compared to a previousversion of the system information that was in use at a previous point intime wherein the previous point in time is identified based on apredetermined time difference; and an indication of a current versionnumber, the version number being incremented at each system informationchange, the version number being selected from a circular list of nelements, with n≥2.
 6. The base station of claim 1, further configuredto: provide the second synchronisation signal as two or more separatesignals forming together the second synchronisation signal.
 7. The basestation of claim 1, further configured to: broadcast the secondsynchronisation signal using two or more separate frequency bands. 8.The base station of claim 7, further configured to broadcast the secondsynchronisation signal according to one or more of: a transmission of afirst portion of the second synchronisation signal as a continuoussignal in a first of the two or more separate frequency bands or as anon-contiguous signal in the first frequency band; and a transmission ofa second portion of the second synchronisation signal as a continuoussignal in a second of the two or more separate frequency bands or as anon-contiguous signal in the second frequency band.
 9. A method oftransmitting system related information in a mobile telecommunicationsnetwork, the network comprising a base station configured to transmitsystem information for the cell provided by the base station, the methodcomprising: broadcasting, by the base station, a first synchronisationsignal for use for terminals to achieve synchronisation with the cell;broadcasting, by the base station, a second synchronisation signal molefrequently than the first synchronisation signal, wherein the secondsynchronisation signal provides version information regarding thecurrent version of the system information for the cell.
 10. The methodof claim 9, wherein the first synchronisation signal is transmittedperiodically at a first time frequency and the second synchronisationsignal is transmitted periodically at a second time frequency, thesecond time frequency being higher than the first time frequency. 11.The method of claim 9, wherein the second synchronisation signal istransmitted based on one or both of: a sequence that differs from asequence used for transmitting the first synchronisation signal; and ascrambling configuration that differs from a scrambling configurationused to transmit the first synchronisation signal.
 12. The method ofclaim 9, wherein the second synchronisation signal is transmitted basedon a number, the number indicating the current version of the systeminformation for the cell, wherein the number is used to derive one orboth of a sequence and a scrambling configuration for transmitting thesecond synchronisation signal.
 13. The method of claim 9 wherein theversion information regarding the current version of the systeminformation for the cell comprises one or more of: an indication thatthe current version of the system information has changed compared to aprevious version of the system information that was in use at a previouspoint in time; an indication that the current version of the systeminformation has changed compared to a previous version of the systeminformation that was in use at a previous point in time wherein theprevious point in time is identified based on a predetermined timedifference; and an indication of a current version number, the versionnumber being incremented at each system information change, the versionnumber being selected from a circular list of n elements, with n≥2. 14.The method of claim 9, wherein the second synchronisation signal isprovided as two or more separate signals forming together the secondsynchronisation signal.
 15. The method of claim 9, wherein the secondsynchronisation signal is transmitted using two or more separatefrequency bands.
 16. Circuitry for an infrastructure equipment for amobile telecommunications network, the circuitry configured to: transmitsystem information for a cell of the mobile telecommunications network;broadcast a first synchronization signal for use for terminal to achievesynchronization with the cell; and broadcast a second synchronisationsignal more frequently than the first synchronisation signal, whereinthe second synchronisation signal provides version information regardingthe current version of the system information for the cell.